An amusing little deception

[Michael GilliganParticipant @michaelgilligan61133]

Whilst I was out and about, yesterday, I bought two short lengths of [apparently] substantial Loudspeaker Cable at a modest price

… presumably left-overs from an installation

.

.

.

Imagine my surprise when I discovered the plastic tubes within the twist of copper strands !

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

 

As the old saying goes: BullS**t Baffles Brains !

https://www.futureshop.co.uk/qed-xt25-speaker-cable-custom-length

MichaelG.

.

[FulmenParticipant @fulmen]

I don’t think it’s intended as deception. After all they show the construction in the information, and as long as they have 2.5mm cross section you get what you paid for. They also explain why it’s made this way. Skin effect is a well known effect in AC transmission, ask any HiFi nut (please don’t, they’re boring AF).

[Michael GilliganParticipant @michaelgilligan61133]

Don’t worry … I got what I paid-for [it was very reasonably priced], and I know a little about skin-effects.

The ‘deception’ is simply a matter of it not being what it looks like.

[appropriate usage, considering the etymology, I think]

The link to QED’s description, of course, was only found after I looked at the marking on the cable.

MichaelG.

[Robert Atkinson 2Participant @robertatkinson2]

Probally less of a con than this speaker lead

Cardas Clear Beyond Speaker Cable

Or a mains lead of 99.9999% pure copper

Cardas Clear Beyond Power XL Cable

Apparently the first metre makes all the difference, the cheapo cable in the wall doesn’t matter 😉

Robert.

[noel shelleyParticipant @noelshelley55608]

If you knew it was 2.5 sqmm and it has a plastic core did it not look like 4sqmm ? Noel.

[noel shelley]

On noel shelley Said:

If you knew it was 2.5 sqmm and it has a plastic core did it not look like 4sqmm ? Noel.

Mmmm … Not sure to whom that question is addressed

But you can see [from my first photo] what it looks like

… and I bought it on ‘first appearances’

MichaelG.

.

UPDATE: Here’s the White Paper

https://www.qed.co.uk/downloads/qed/soundofscience.pdf

The Conclusions on pp21-22 are worth skimming through.

[Michael GilliganParticipant @michaelgilligan61133]

[Neil WyattModerator @neilwyatt]

Audiophile cable theory is marginally more plausible than flat earth theory.

Neil

[Neil WyattModerator @neilwyatt]

To clarify, I’d like to see graphs of conductivity versus frequency comparing a multi-thousands of pounds cable against ordinary two-core mains cable.

Neil

[Fulmen]

On Fulmen Said:

I don’t think it’s intended as deception. …

I think it might be!  There’s a long history of selling stuff to credulous buyers.

Science insists on double-blind testing because the methodology removes conscious and unconscious bias.   When observers are deprived of anything that might confirm their beliefs, they only have the truth to go on, and it shows!

Double blind testing reveal few wine tasters have a genuine skill, whilst a number of blind tests of high-end violins show that concert violinists can’t tell the difference between multi-million classical instruments and modern ones.  Based on sound alone, Stradivarius are inferior to modern instruments.    Interestingly, musicians seem to prefer louder instruments, which modern violins are.   When concert violinists are told what they’re listening to, they much prefer classical.

Double-blind testing has repeatedly been very unkind to audiophiles, but they don’t let it worry them.

Same problem with tools.  People pay over the odds for Myfords, even though there’s no evidence they work better than other makes.   I think if a table were covered in samples of work produced by a mix of Myfords and other lathes, and then another large group of model engineers was asked to identify which were made on Myfords, then the hits would be a random distribution, not proof Myford make an obvious difference.

Likewise amateur radio equipment, motor bikes, wristwatches, cameras, smart phones, fashionable clothing, and other objects of desire.

A university study showed that the purchasing decisions of grizzled professional engineers were influenced by draping scantily clad young women over the equipment.

And as for politicians – no lie is too fat, and when caught out their supporters all lie too!  Apparently large groups of people want the world to be run by dishonest politicians…

Dave

 

[FulmenParticipant @fulmen]

By that sentiment 95% of HiFi is deceptive. Not that I’m arguing against that notion…

[Fulmen]

On Fulmen Said:

By that sentiment 95% of HiFi is deceptive. Not that I’m arguing against that notion…

… very true [in principle if not numerically] … and striving for that last 5% is where the lunatic-fringe spends its money.

”diminishing returns” is thus defined.

MichaelG.

[V8EngParticipant @v8eng]

Having developed very defective hearing means that I do not have to worry about such exotica anymore.

Never did anyway, nothing wrong with a length of figure of 8 twin😉

 

[Dod MoleParticipant @georgeclarihew]

And there was me thinking that the tubes were them new-fangled wire protected fibre optic audio cables or have i come up with a new dual purpose product.

My potentially patentable idea.

[duncan webster 1Participant @duncanwebster1]

Let’s not venture into golf bats, I suspect there is similar hype there.

[Neil Wyatt]

On Neil Wyatt Said:

Audiophile cable theory is marginally more plausible than flat earth theory.

Neil

Agreed, but there may be enough in the physics of AC flowing in cables to start a good story.

Litz Wire improves the performance of low radio frequency inductors by reducing skin effect.  But it improves Q, important for selectivity in radios, and the wire is only of value between 60kHz and, maybe, 2000kHz.

Wikipedia’s Litz Wire article gives these figures for skin effect:

At 60 Hz, the skin depth of a copper wire is about 7.6 millimetres (0.30 in).
At 60,000 Hz (60 kHz), the skin depth of copper wire is about 0.25 millimetres (0.0098 in).
At 6,000,000 Hz (6 MHz) [5] the skin depth of copper wire is about 25 micrometres (0.00098 in).

So, at audio frequencies, skin effect will be detectable in mains cable if you have the right equipment, but that isn’t a pair of ears.   The cable’s capacity and inductance will also have a detectable effect, but again not with a human ear’ole.   And if the distortion was detectable by humans, the easiest way to correct it would be by tweaking the amplifier’s tone control.

Transmission cables for radio frequencies do require special design, and mains wire isn’t suitable for RF. Or for low amplitude audio inputs.  I guess audiophiles who dig into the physics of RF cabling might assume the maths applies to AF, and that it somehow reveals a problem worth fixing by spending big bucks.

Dave

[Nigel Graham 2Participant @nigelgraham2]

Looks like advertising exploiting the old maxim that a little learning is a dangerous thing…

 

[Martin WParticipant @martinw]

Read this brochure and see what you are missing. What the marvels of modern technology can do to a piece of twisted copper wire, I will miss the joys of a bit of wire heterodyning as an audio signal passes through it.

[Michael GilliganParticipant @michaelgilligan61133]

Thanks, Martin 🙂

An astonishing rabbit-hole:

https://www.nordost.com/

… Check the Downloads page.

.

Mr Reynolds looks a very contented Cat:

https://www.nordost.com/downloads/HiFi%20_GuideToCables_Reynolds_HR.pdf

MichaelG.

[Michael Gilligan]

On Michael Gilligan Said:

On Fulmen Said:

By that sentiment 95% of HiFi is deceptive. Not that I’m arguing against that notion…

… very true [in principle if not numerically] … and striving for that last 5% is where the lunatic-fringe spends its money.

”diminishing returns” is thus defined.

MichaelG.

I expect some no engineering types have the same view of chasing a 3 decimal place number when they feel 1 decimal place will do😂

[Mark RandParticipant @markrand96270]

Skin effect is a very real thing, however it isn’t measurable (let alone audible) in 2.5mm^2 solid core copper below 25kHz…

Flexible 2 core mains cable is excellent speaker cable. Use more cores if you have separate driver connections 😀

[noel shelleyParticipant @noelshelley55608]

All very interesting, a friend of mine spent his working days gold or silver plating box section for wave guides for military radar. May be that’s why speaker leads cost many £k. Noel.

[CirclipParticipant @circlip]

Oh what an amusing conspiracy theory. Perhaps it takes a dim wit like me to recognise that the plastic cores are different colours? Seems useful that when you’re fitting the ends with connectors OR NOT, you don’t need a test meter to determine which conductor is which with a clear plastic outer sheath?

DOH!

Regards  Ian

 

Perhaps SOME subjects are posted to generate forum padding?

 

[noel shelley]

On noel shelley Said:

All very interesting, a friend of mine spent his working days gold or silver plating box section for wave guides for military radar. May be that’s why speaker leads cost many £k. Noel.

It’s worth silver-plating high-performance radio-frequency wire, or even using solid Silver, because Silver is more conductive,  less lossy, than Copper.

But not the main reason for silver-plating, which is to prevent corrosion.  This causes trouble at connectors, and losses inside wave-guides.   When used on connectors and wire, Silver has the useful property that Silver Oxide is conductive, making the system more reliable than plain Copper.   Gold doesn’t corrode at all, but is expensive, even when thinly applied.

Interestingly, at UHF and SHF no current should flow in the metal-work at all.  Power is guided along the tunnel, not carried by the metal.  At these frequencies, energy moves as a wave travelling in space, and the power isn’t transferred in the same way as electrons in a solid conductor.

Waveguides can misbehave.  Ideally a waveguide should be empty, a vacuum, because the atmosphere is lossy, and water and dirt are even worse.   The surface of the waveguide needs to be clean.   Surface corrosion inside a wave-guide absorbs power and cause unwanted reflections.  A lot of effort goes into keeping waveguide in good working order, especially in hostile environments.

The design is very different from 50Hz or DC.

Dave

[Author]

Posts